Paleo Profile: Mexico’s “Bird Mimic”

Struthiomimus - a relative of the newly-named Tototlmimus - at the Oxford Natural History Museum. Photo by Brian Switek.
Struthiomimus – a relative of the newly-named Tototlmimus – at the Oxford Natural History Museum. Photo by Brian Switek.

North America has been a dinosaur hotspot for a century and a half. The Bone Wars of the 19th century, the Second Jurassic Dinosaur Rush of the early 20th, and the continuing profusion of new species and specimens all rely on the fossil riches held in the Mesozoic rocks of Canada and the United States. But the dinosaurs just to the south, in Central America, are only just now starting to stalk into the light. The latest to trot out into view is Tototlmimus, Mexico’s “bird mimic”.

For the moment, at least, the new dinosaur isn’t much to look at. Pieces of the feet and the hands are the only parts yet known. But paleontologist Claudia Inés Serrano-Brañas and colleagues make the case that these 72 million year old fragments really do represent a previously-unknown ornithomimid dinosaur that lived along the southern stretch of the long-lost subcontinent Laramidia. The articulation of the foot bones called metatarsals and the shape of one of the toe claws indicate that this dinosaur was an different from closely-related contemporaries that lived further north.

And Tototlmimus isn’t the only dinosaur of its kind found in Mexico. Martha Carolina Aguillon Martinez documented additional ornithomimids found near Coahuila, to the southeast of Sonora, in her 2010 thesis and hypothesized that the bones belonged to a new species. Theses are among the many mystery dinosaurs coming out of this part of the world, and, along with new finds in the U.S. and Canada, they’re starting to highlight the evolutionary explosion dinosaurs underwent in the Late Cretaceous. The dinosaurs found in this 80 to 70 million year old window vary along the latitudes and from basin to basin – pockets of novelty scattered across Laramidia. Finding and identifying the unexpected number of new dinosaur species is just the first step in figuring out why this span of time was so good for dinosaurian novelty.

Foot bones of Tototlmimus in multiple views. From Serrano-Brañas et al., 2015.
Foot bones of Tototlmimus in multiple views. From Serrano-Brañas et al., 2015.

Fossil Facts

Name: Tototlmimus packardensis

Meaning: “Bird mimic of the Packard Shale”, the word “Tototl” meaning “bird” in Náhuatl and the species name referring to the formation in which the dinosaur was found.

Age: Around 72 million years old.

Where in the world?: Sonora, northwestern Mexico.

What sort of critter?: One of the superficially ostrich-like ornithomimid dinosaurs.

Size: Comparable in size to related dinosaurs like Gallimimus.

How much of the creature’s body is known?: Fragments of the hands and feet.

References:

Inés Serrano-Brañas, C., Torres-Rodríguez, E., Reyes-Luna, P., González-Ramírez, I., González-León, C. 2015. A new ornithomimid dinosaur from the Upper Cretaceous Packard Shale Formation (Cabullona Group) Sonora, Mexico. Cretaceous Research. doi: 10.1016/j.cretres.2015.08.013

Rivera-Sylva, H., Carpenter, K. 2014. “Mexican Saurischian Dinosaurs” in Dinosaurs and Other Reptiles From the Mesozoic of Mexico, Rivera-Sylva, H., Carpenter, K., and Frey, E., eds. Bloomington: Indiana University Press. pp. 143-155

Previous Paleo Profiles:

The Unfortunate Dragon
The Cross Lizard
The South China Lizard
Zhenyuan Sun’s dragon
The Fascinating Scrap
The Sloth Claw
The Hefty Kangaroo
Mathison’s Fox
Scar Face
The Rain-Maker Lizard
“Lightning Claw”
The Ancient Agama
The Hell-Hound
The Cutting Shears of Kimbeto Wash
The False Moose
“Miss Piggy” the Prehistoric Turtle

3 thoughts on “Paleo Profile: Mexico’s “Bird Mimic”

  1. A little nit-picky maybe but Mexico is definitely part of North America, not Central America. Otherwise good read. I always enjoy these profiles.

    1. If we’re being picky Matt, then there IS no Central America, only North or South. Whenever people bother making a distinction between North and Central America, Mexico is invariably included in the latter.

      BTW Brian, is this new ornithomimid really as big as Gallimimus? From my understanding, Gallimimus is the largest ornithomimid other than Deinocheirus. Your wording suggests you instead meant something along the lines that Tototlmimus was average sized.

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